A global navigation satellite system (GNSS) utilizes an earth-orbiting constellation of a plurality of satellites each broadcasting GNSS signals which indicates its precise location and ranging information. From particular locations on or near the earth, GNSS receivers may detect valid GNSS signals and take various GNSS measurements such as pseudorange, carrier phase, and/or Doppler to calculate navigation information such as GNSS receiver position, velocity, and time. The American global positioning system (GPS), the Russian GLObal NAvigation Satellite System (GLONASS), the European Galileo positioning system and the Chinese Compass navigation system are examples of GNSSs.
The GNSS may be a direct sequence spread spectrum (DSSS) based system such as, for example, a code division multiple access (CDMA) based system. A GNSS satellite may transmit signals modulated with a spreading code such as, for example, a pseudorandom noise (PRN) code. A GNSS receiver may process the received signals by correlating or de-spreading the signals with the same spreading code.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings.